Method of making airplane propeller blade shanks



Jun 1954 F. A. GRUETJEN METHOD OF MAKING AIRPLANE PROPELLER BLADE SHANKS Filed Aug. 15, 1949 4 Shegts-Sheet l INVENTOR. Freda rick A. Grue en BY m ,w/aaa ATTORNEYS.

June 1, 1954 GRUETJEN 2,679,682

METHOD OF MAKING AIRPLANE PROPELLER BLADE SHANKS Filed Aug. 15, 1949 FIG.5. FIG. 9.

4 Sheets-Sheet 2 F1510. Frail.

F 1 1 15.13. H614. 2 z g INVENTOR. Frederick A. Gruegen wn/wz MM AT TURNEYS.

June 1, 1

Filed Aug.

F. A. GRUETJEN WELD LINE METHOD OF MAKING AIRPLANE PROPELLER BLADE SHANKS 4 Sheets-Sheet 3 WELD LINE.

INVENTOR. Frederick AGZ'ueyen ATTORNEYS.

J1me 1954 F. A. GRUETJEN METHOD OF MAKING AIRPLANE PROPELLER BLADE SHANKS 4 Sheets-Sheet 4 Filed Aug. 15, 1949 WELD LINE.

' INVENTOR. Frederick A.Grue {yen BY m 1 MM ATTORNEYS.

Patented June 1, 1954 METHOD OF MAKINGAIRPLANE PROPELLER BLADE SHANKS Frederick A. Gruetjen, Milwaukee, Wis., assignor to A. ;..Smith Corporation, Milwaukee, Wis., a corporation of New York Application. August 15, 1949, Serial No. 110,430

1 Claim. (01. 29-156.8)

This invention relates to shank members for aircraft propeller blades and to the method of making the same.

It has been the general prior practice in blades of this type to form the blade shank in one piece with the hollow outer camber member, or if the shank member is formed separately from the blade proper it has most generally been fabricated in halves in'such fashion that considerable machining is necessary to'arrive at weld surfaces which are true and straight. Likewise, if'the blade is fabricated so that each camber member blank includes-one half of the shank forming portion of the blade, it is fairly costly tomachine the halves to attain surfaces which" may be properly welded.

The object of this invention is to provide a method whereby shank members forh-ollow aircraft propellers may be produced from successive rolling and forging steps which eliminates considerable machining of surfaces which are to be welded in the formation of'the shank.

A further object is :to provideashankmember for'hollow aircraft propellers which is'rcontour rolled and subsequently subjected to successive forging operations to"providerdensev compact welding surfaces requiring very little, if any, machining before the surfaces are joined together.

Another object is to provide: a shank for aircraft propellers by a method in which theunit stresses in the high stress areas of the shank are maintained aslow as possible.

Another object is to provide a method for producingshanks for aircraft propeller blades which method includes a bending operation of the partially formed shank-which reducesseverity of subsequent forging operations andthereby maintains as low as possible, stretching of. the metal.

Other objects and advantages. will be set forth in the description of an embodiment of the invention illustrated in the accompanying drawings.

In the drawings:

Figure 1 is a plan view of a shank for aircraft propellers formed by the method ofthe invention;

Fig. 2 is a longitudinal side view;

Fig. 3 is a transverse sectional view taken on line 3-3 of Fig. 2;

Fig. 4 is a transverse sectional view taken on line 4-4 of Fig. 2;

Fig. 5 is a plan view of a fiat plate utilized in making a half of a shank member prior to contour rolling of the same.

Fig. 6 is an end view .of. the flat plateshown in Fig. 5;

' the blank may be accomplished by passing. the

Fig. '7 is a plan view on a larger'scale of" the metal blank of Fig. 5' after the same hasbeen hot rolled to taper it throughout the major 'portion of its length and to provide thickenedportions at the sides and ends thereof forwelding purposes and to provide a thickened configuration at the center for attachment of cuffs;

Fig. 8 is a view taken on line S-B'of Fig. 7;

Figs.'9, 10, 11, 12, 13 and 14 aresectionalxviews taken on lines 9-9, Ill-l0, Il-l l, l2-l2, l3-i3 and I 4-l4, respectively, of Fig. 7;

Fig. 15 is a view similar toFig; 8 of'thecontoured blank after the same hasbeen subjected to a bending operation-but prior to U-formin'g the blank; I

Fig. 16 is a plan view of the shank'half after the same has been U-formed;

Fig. 1'7 is a side elevational view of Fig. 16

Figs. 18, 19, 20, 21, 22 and 23'are transverse sectional views taken on lines lB-IB, Iii-l9, 20-20, 2l-2I, 22-22 and 23-23, respectively, of Fig. 17;

Fig. 24 is a plan view of the shank half after the final forging step showing the edges prepared for welding and formed cuffseats in the upper portion of the shank half;

Fig. 25 is aside elevationalview of Fig. 24; and

Figs. 26, 2'7, 28, 29, 30 and 31 aretransverse sectional views taken on lines 26-26, 21-21, 28-28, 29-29, 30-30 and 31-31, respectively, of Fig. 25.

In accordance with the invention, a substantially rectangular blank I of a shape such as shown in Fig. 5 is cut from flat plate stock of suitable thickness.

This blank is heated .to a. temperature suitable for rolling and then fed longitudinally, preferably by a mechanical loader, into a pair of rolls which elongates and tapers .a substantial portion of the blank. At the same time the blank is contouredto provide substantially thick longitudinal edges 2 and a substantially thick transverse edge 3 for welding. Asubstantial portion of the body of the blank, intermediate the edges of'the same is reduced inthickness while the right half of the blank as seen in Fig. '7, is providedwith an upstanding ridge 2 of substantially theconfiguration shown in Figs. 12, Band 14. Itwillbe noted that the ridge 4 gradually increases in-height as it approaches the edge 3. A suitable metal buildup or thickened portion 5 isprovided'at-the-center near the inner .end of ridge 4 to provide, for a drainhole in each half of the shank.

The elongating, tapering and-contouring of heated blank between a pair of rolls, the upper of which is provided with suitable indentations to provide the desired edges and upstanding ridge while the bottom roll is smooth, or the blank may be formed by placing it on a suitable die and rolling it to the desired configuration.

For the purpose of example only, the blank shown in Fig. 5 may be approximately 9"/; inches long and inches wide. After the blank is contour rolled it may be approximately 16 inches long and 15 inches wide. It will be appreciated that to accomplish this change in length there will of necessity, have to be employed a rather heavy reduction pass which results in a substantial grain flow in the direction of travel of the blank.

After the blank is contour rolled it is substantially fiat. In forming a shank half from this blank it is necessary to U-form the same which requires rather severe forging which in turn is likely to produce severe unit stresses in certain portions of the contoured blank due to stretching of the metal. In order to keep any unit stresses at a minimum it has been found that it is desirable to bend the blank prior to the U-forming step. This may be accomplished with any suitable mechanism which is capable of bending a major portion of the contoured blank to a form such as shown sectional in Fig. 15. As there shown the central portion. of the blank is inclined with respect to the inner and outer end portions of the blank which are disposed on parallel planes after the bending is completed. Preferably the upper surface of the blank is bent in such a manner that it will conform substantially to the inner surface of the die used in the consequent U-forming step. It will be understood that the bending operation tends to reduce the severity of stress due to stretching of the metal in subsequent successive operations.

The bent shank half shown in Fig. 15 is next placed on a die of substantially U formation where the shank half is formed to U-shape with the upstanding ridge 4 being disposed on the outer surface of the shank half. As shown in Figs. 16 and 17, it will be noted that the left end of the blank is substantially semi-cylindrical to a station indicated by section line |9l9. From this station, however, to the right hand edge the contour of the unit changes quite markedly in that there is a continuous upward slope to the upper wall, while the side walls gradually merge closer together until at the narrowest station of the blank, section 23, they become parallel to each other. The curved surfaces are blended so that a minimum of resistance is encountered when the aircraft propelled with the shank attached is in use. Figs. 18, 19, 20, 21, 22 and 23 are typical sections of the shank half at their respective stations. It will be noted that the longitudinal side edges 3 which are welded to like edges of a complementary shank half are of substantial depth; for example, there may be edges inch in depth extending from the weld line or joining line between the shank halves.

It is the general practice in forming halves of units of the general type to which this invention is directed, that the longitudinal edges which are to be welded generally necessitate a machining operation to straighten the edges which are to be later welded. The following step of this invention not only eliminates the necessity of this but in addition, compacts the edges to be 4 welded into a firm dense mass which results in a more uniform and stronger weld.

After the shank half has been formed to U- shape, as above described, the shank half is set on its longitudinal edges and forged by a die member which flattens it so that the metal in the edges is compacted and the depth of the edges reduced a considerable amount. For instance, a longitudinal edge of an inch deep from the proposed welding line may be reduced as much as inch. During this forming operation the upstanding ridge 4 is coined to provide sharp edges that define a seat for the reception of a cuff member which is welded to the shank half.

The excess metal in the longitudinal edges is made to flow upwardly by the pressure of forging so that it fills out any irregularities in the side walls due to necking of the metal and also fills in any voids or semi-voids between the ridge 4 and the die enclosing the shank during coining of the shoulders. This step compacts the metal throughout the half section which results in a substantially dense firm forged half section.

The change in configuration of ridge 4 may best be understood by comparing Figs. 17 and 25 and sectional views shown in Figs. 21, 22 and 23 with those shown in Figs. 29, 30 and 31. During this final forging operation it is generally practicable to provide index points for drainholes and a hot air duct which may be drilled later.

The shank halves are assembled with their longitudinal edges abutting and are flash welded together. During this operation the metal between the weld lines and the outer edges of the halves is removed by the welding.

The invention provides a method for producing shanks for aircraft propellers which is relatively simple and quite economical as compared with methods heretofore practiced. The forging step which compacts the metal along the longitudinal edges of the shank halves and which at the same time coins the corners of the upstanding ridge for the reception of cuff members is economical and results in a sounder shank member than heretofore produced.

Various embodiments of the invention may be employed within the scope of the accompanying claim.

I claim:

In a method of making a shank for a hollow aircraft propeller blade, the steps which comprise longitudinally contour rolling a heated plate-like blank to elongate and taper the blank longitudinally throughout a major part of its length and simultaneously produce generally thick longitudinal edges and a substantially thick inner edge as well as an upstanding reinforcing ridge of generally U-shape beginning at substantially the central portion of the blank and increasing in height to adjacent the inner end of the blank, bending the rolled blank transversely to dispose the major portion of the blank comprising the central portion thereof inclined with respect to the inner and outer end portions of the blank, with said latter end portions being disposed on parallel planes after the bending is completed, pressing the blank longitudinally to substantially U-shape in transverse crosssection with said upstanding ridge bein disposed on the outer surface of the blank, the blank being thereby pressed to semi-cylindrical shape at the outer end and the side walls thereof gradually merged to a parallel extent at the inner end, forging the longitudinal References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,569,800 Dicks Jan. 12, 1926 1,840,059 Smith Jan. 5, 1932 1,921,486 Seiferth Aug. 8, 1933 Number 10 Number Name Date Enos July 30, 1946 Berliner Nov. 18, 1947 Koppel Mar. 29, 1949 Gruetjen May 31, 1949 Heath Jan. 3, 1950 Gruetjen Dec. 26, 1950 FOREIGN PATENTS Country Date France Oct. 25, 1906 

